doubleclutchinweasel Posted October 6, 2022 Share Posted October 6, 2022 It's for a different setup (R model), but maybe this will give you something to think about at least. The "Stop Light Switch" is in the "trailer service" line, downstream of the double check valve. This way, the brake lights come on if either the trolley valve or the treadle valve are operated. The schematic shows this a long way from the treadle, but, in reality, it was right there at it. Quote "Eagles may soar, but weasels don't get sucked into jet engines." Link to comment Share on other sites More sharing options...
Freightrain Posted October 6, 2022 Share Posted October 6, 2022 6 hours ago, skydawg said: So I can put the switch in one of the trailer air line fittings that are presently plugged? Just move it to the other side of the TP valve that it is in now. It should say "Service". 1 Quote Larry 1959 B61 Liv'n Large...................... Charter member of the "MACK PACK" Link to comment Share on other sites More sharing options...
Popular Post skydawg Posted October 7, 2022 Author Popular Post Share Posted October 7, 2022 We have brake lights! Putting the switch in the left trailer line did the trick.Many thanks to all who responded. 4 Quote Link to comment Share on other sites More sharing options...
skydawg Posted October 15, 2022 Author Share Posted October 15, 2022 Not fixed after all.With the tractor Protection switched to Emergency,there`s no air pressure to either trailer fitting.TP switched to normal,brake lights come on w/air brake switch in either trailer line when air pressure builds in the tank.Does this indicate a bad brake valve under the pedal? Quote Link to comment Share on other sites More sharing options...
Brocky Posted October 15, 2022 Share Posted October 15, 2022 (edited) Probably not?? Do your brake lights come on with the foot pedal (no hand valve) in the Normal position??? If so, and you can see the brakes apply, your foot pedal should be OK.. There should be TWO stop light pressure switches.. The primary should(????) be on the cowl / firewall.. not too far from the underside of the foot pedal. In the service line which applies air to the tractor brakes when you step on the pedal. The switch you have in the trailer service line is there so you have brake lights when you use the hand valve ONLY.. In the emergency position there is no air to the trailer.. Edited October 15, 2022 by Brocky Quote Brocky Link to comment Share on other sites More sharing options...
skydawg Posted October 15, 2022 Author Share Posted October 15, 2022 With the tractor protection in Normal position,the brake lights are always on as long as there`s air built up,w/no brake pedal being used.There`s air pressure always present in either trailer air line fitting when the TP switch is in the NORMAL position,with no brake pedal involved. Quote Link to comment Share on other sites More sharing options...
Freightrain Posted October 16, 2022 Share Posted October 16, 2022 The brake light switch needs to be moved before the TP valve, not after. That is the problem. Was it in that location when you bought the truck? It just needs move upstream towards the brake pedal, in a location that is not affected by anything else. Quote Larry 1959 B61 Liv'n Large...................... Charter member of the "MACK PACK" Link to comment Share on other sites More sharing options...
doubleclutchinweasel Posted October 17, 2022 Share Posted October 17, 2022 19 hours ago, Freightrain said: The brake light switch needs to be moved before the TP valve, not after. That is the problem. Was it in that location when you bought the truck? It just needs move upstream towards the brake pedal, in a location that is not affected by anything else. That's the ticket right there. Put the switch into the "trailer-service" line coming out of the double check valve, headed toward the tractor protection valve. This line should have pressure on it any time the foot valve or trolley valve is opened, regardless of the TP valve position. On my R, the double check valve was right at the foot valve. Not sure where it is on a B. If you have air pressure in the trailer "trailer-service" line (with TP valve to "normal" and no foot valve or trolley valve open), there is a problem somewhere else. With the TP valve to "normal", there should be air in the "trailer-emergency" line only (it charges the air system on the trailer). Only when you open the foot valve or trolley valve should you get air to the "trailer-service" line. Possibly leaking through trolley valve? Or a bad TP valve? Setting the TP valve to "emergency" kills all the air going to the trailer. On my R, there was a second switch that caused the brake lights to come on when the parking brakes were applied. It was normally closed, so it opened and shut off the lights when you applied air to overcome the spring brakes. When you dumped the air to allow the spring brakes to engage, the switch closed and turned on the lights. So, the brake lights were on any time the key was on and the parking brakes were set. Incidentally, if you have no intention of ever hooking up a trailer, you could conceivable put the switch into a line that feeds the brakes on the tractor. But, I think it would be just as easy to tee it into the "trailer-service" line between the double check valve and the tractor protection valve. Anyway, get the switch moved to a better spot first and see if everything works better. 1 Quote "Eagles may soar, but weasels don't get sucked into jet engines." Link to comment Share on other sites More sharing options...
mechohaulic Posted October 17, 2022 Share Posted October 17, 2022 there's a saying "many hands make light work" ::: in the mechanical world " many hands sure screw up a lot of simple projects. L9000 ford I'm working on now show how many hands did their thing with new wires and way tooo many butt connectors. no brake lights to trailer when stepping on pedal = great brake lights when parked and key on. Quote Link to comment Share on other sites More sharing options...
Freightrain Posted October 17, 2022 Share Posted October 17, 2022 My brake light switch is right under back of cab on left frame rail, I'm guessing in the service line going to the rear brakes? Im also guessing it tees off to the TP valve. Quote Larry 1959 B61 Liv'n Large...................... Charter member of the "MACK PACK" Link to comment Share on other sites More sharing options...
skydawg Posted October 17, 2022 Author Share Posted October 17, 2022 (edited) I finally found the original switch,under the cab,inside the frame rail on top of a double check valve,according to a B schematic.I hope it`s just the wiring that`s bad because it looks like it would have to be replaced w/ the same model.It doesn`t thread into the check valve,it`s attached by 2 screws.Maybe it can be fixed,if an exact replacement isn`t available.Where would I find the trolley valve? Thanks everyone for responding,I obviously have a lot to learn. Edited October 17, 2022 by skydawg added to post Quote Link to comment Share on other sites More sharing options...
Freightrain Posted October 17, 2022 Share Posted October 17, 2022 Trolley valve is the hand brake on the column. It manually operates only the trailer brakes. Quote Larry 1959 B61 Liv'n Large...................... Charter member of the "MACK PACK" Link to comment Share on other sites More sharing options...
Popular Post Brocky Posted October 17, 2022 Popular Post Share Posted October 17, 2022 1 hour ago, Freightrain said: Trolley valve is the hand brake on the column. It manually operates only the trailer brakes. Technically speaking it would be named: The hand operated manual trailer brake application valve, but it has many "nicknames" starting with hand, trolley, spike, Johnson bar, and other similar names. 2 1 Quote Brocky Link to comment Share on other sites More sharing options...
doubleclutchinweasel Posted October 28, 2022 Share Posted October 28, 2022 Did you ever get this sorted out? Quote "Eagles may soar, but weasels don't get sucked into jet engines." Link to comment Share on other sites More sharing options...
doubleclutchinweasel Posted October 28, 2022 Share Posted October 28, 2022 (edited) On 10/17/2022 at 1:02 PM, Brocky said: Technically speaking it would be named: The hand operated manual trailer brake application valve, but it has many "nicknames" starting with hand, trolley, spike, Johnson bar, and other similar names. By the way, we also called the forward/reverse lever in a direct-drive Caterpillar tractor the "Johnson Bar". I think the steam locomotive engineers used that term for other things, too. EDIT: A quick search shows that steam locomotives' "reversing bar" was sometimes called the Johnson Bar. I guess that's where the Cat guys got it. Edited October 28, 2022 by doubleclutchinweasel 1 Quote "Eagles may soar, but weasels don't get sucked into jet engines." Link to comment Share on other sites More sharing options...
Freightrain Posted October 28, 2022 Share Posted October 28, 2022 Johnson.......oh that reminds me of this commercial. Lol...... 1 1 Quote Larry 1959 B61 Liv'n Large...................... Charter member of the "MACK PACK" Link to comment Share on other sites More sharing options...
doubleclutchinweasel Posted October 28, 2022 Share Posted October 28, 2022 I couldn't get it to load right now. Is that Raymond J. Johnson, Junior? Quote "Eagles may soar, but weasels don't get sucked into jet engines." Link to comment Share on other sites More sharing options...
doubleclutchinweasel Posted October 28, 2022 Share Posted October 28, 2022 Yep. It loaded. That's what I thought...or was afraid of! LMAO! 1 Quote "Eagles may soar, but weasels don't get sucked into jet engines." Link to comment Share on other sites More sharing options...
Freightrain Posted October 29, 2022 Share Posted October 29, 2022 Any time the name Johnson comes up....that stupid commercial rings in my head......LOL. 1 Quote Larry 1959 B61 Liv'n Large...................... Charter member of the "MACK PACK" Link to comment Share on other sites More sharing options...
skydawg Posted November 5, 2022 Author Share Posted November 5, 2022 Yes,finally have brake lights.After new wiring,still no joy.Located,the original switch atop the double check valve,opened it and cleaned the contacts,brake lights are back in business.Thanks to all responders. 1 Quote Link to comment Share on other sites More sharing options...
Freightrain Posted November 6, 2022 Share Posted November 6, 2022 Thanks for the update. Quote Larry 1959 B61 Liv'n Large...................... Charter member of the "MACK PACK" Link to comment Share on other sites More sharing options...
doubleclutchinweasel Posted November 7, 2022 Share Posted November 7, 2022 On 11/5/2022 at 6:37 PM, skydawg said: Yes,finally have brake lights.After new wiring,still no joy.Located,the original switch atop the double check valve,opened it and cleaned the contacts,brake lights are back in business.Thanks to all responders. Glad to hear you found the switch and got it sorted out. Plus, you were able to keep it original. Thanks for posting the follow-up. Follow-ups are very helpful for the next guy with a similar issue. Quote "Eagles may soar, but weasels don't get sucked into jet engines." Link to comment Share on other sites More sharing options...
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